"This is the toughest and biggest challenge of my life, in terms of moviemaking," he said recently. "But I love it. I love the challenge."

The film, about an unmanned runaway train carrying hazardous cargo, stars Denzel Washington, with whom Scott has worked several times before, and Chris Pine. Scott talked about trying to make the film, which was inspired by true events, as realistic as possible, how he came up with the complex set pieces and more.

Question: The action scenes are very realistic. How did you shoot them?

Answer: My concept, or my goal, was to not to be inhibited by a train moving at 70 miles per hour. All the techniques I use on a stage or a studio, I was going to take to that 70-miles per hour train, with tracking shots and long lenses. There's a certain reality when you put actors in a train running at that speed, with the noise and the wind and the insanity. You get a different performance. The guys just rise to the occasion.

Q: What appealed to you about the story?

A: It was a great vehicle for me because you've got two stories. You've got two worlds. You've got these two guys having to come to terms with their differences and get on their game and shut this train down, and you're looking at this third character, which I call "the Beast." It's 100 thousand tons of steel and it looks like it's running 100 miles per hour.

Q: What work did you do beforehand to ensure the action was realistic?

A: Before I commit to a movie, I'll go spend a week or two weeks or a month, whether it's in Pennsylvania or Mexico City. And then I'll say, "OK, I get it, this is a world I want to touch and be part of for 18 months of my life." But standing in those railyards with those trains blowing by you at 60, 70 miles per hour, that's what I try to capture on film. That's what I loved. It's the power, the weight, the noise, it's everything. It's this monolithic beast of 100 thousand tons of steel coming past you.

Q: Were you worried about balancing the action and the acting?

A: That was my challenge. That was the strengths and weaknesses. If I (messed) it up, the action aspect of it could have overtaken the performance. But it's great. I worked with two of the greatest actors in the business.